It is known to introduce into water about to pass through a heat exchanger, such as the condenser of an electric generating power plant, cleaning bodies whose function it is to wipe clean the heat exchange surfaces of the condenser upon entrainment of these bodies through the tube bundle of the heat exchanger.
When cleaning is accomplished by the use of such cleaning bodies, hereinafter referred to as cleaning balls and which can be composed of a foam synthetic resin, the cleaning bodies must be captured or recovered from the water downstream of the heat exchanger and, after such capture, can be recirculated to a location upstream of the condenser for reentrainment in the cooling water. As a result, the cooling balls are recirculated in a ball recirculation and cleaning system.
It is known to provide a grate, screen or grid with a bar spacing less than the diameter of the balls, in the path of the water downstream of the condenser to recover the cleaning balls therefrom, to provide a trough or the like at a low point along the stream in which the captured balls are collected and to communicate with this trough via a pipe to allow the balls to be withdrawn from the trough for recirculation.
More specifically, and as should be clear from the aforementioned copending applications and the earlier patents, it is not uncommon to provide a cleaning ball system wherein a housing in the form of a duct or pipe section has connecting flanges at the upstream and downstream ends of this pipe section to enable it to be connected in the pipeline downstream of the condenser. This pipe section, in turn, may be provided with a ball-capturing sieve which is inclined to the axis of the pipe section and is generally planar so that its downstream end, i.e. its end proximal to the wall of the pipeline, has an elliptical configuration, and means is provided at this downstream end for collecting the balls which, upon capture by the sieve, are guided to the wall of the pipeline at this downstream end. This means can include a pipe for withdrawing the collected balls.
It has been proposed previously to mount the ball-capturing sieve so that it is swingable about an axis orthogonal to the axis of the pipe section into its functional position and out of its functional position. The sieve lies athwart the stream and captures the balls therefrom whereas in its nonfunctional position the sieve lies generally parallel to or along the stream and thus is unable to intercept the balls.
The sieve can be a single member spanning the entire cross section of flow in its functional position, in which case it has an elliptical configuration at each end adapted to lie against the pipe wall. However, two sieve sections may be utilized and can be substantially symmetrically disposed on either side of a median axial plane so that upstream edges of the sieve sections come together in the functional position while the downstream ends of the sieve sections have the elliptical configuration described.
In the functional position, therefore, the two sieve sections have a coping shape, i.e. an inverted V-configuration, but are substantially parallel to one another and to this plane and the flow in the nonfunctional position.
The manner in which the device functions is, of course, the same whether the single sieve is utilized or two sieve sections are employed and throughout this description, therefore, it will be understood that reference to a single sieve or to a pair of sieves are equivalent and interchangeable and that, as far as the present invention is concerned, whatever applies to a sieve section of a double-sieve arrangement will be equally applicable to a single-sieve system except that, in the latter case, the single-sieve will span the entire flow cross section in its functional position whereas in the two-sieve arrangement, each sieve will span only half the flow cross section in the functional position.
As noted previously, in earlier arrangements, the downstream end of the sieve of a single-sieve arrangement or the downstream ends of the sieves of a double-sieve arrangement will be provided with respective collecting troughs, which may also be referred to as collecting boxes because they are generally of a box-like cross section, mounted on the housing or pipe walls and to which the balls are delivered as they are captured by the grate or sieve. Instead of full box-like structures, the ball accumulating or collecting troughs may be defined by baffles or deflectors which likewise are mounted upon the housing or pipe wall.
The pipe communicating with the trough may also be permanently or fixedly mounted on the pipe or pipe wall and serves to enable the balls to be drawn out of the trough.
In practice, this arrangement in which the ball-collecting trough is located at a fixed position on the pipe wall and the sieve or grate has a certain inclination to the axis at least in its functional position, required the entire assembly forming the ball-recovery device to be of considerable length. This poses a serious problem when the ball-collecting device is to be applied to existing condenser installations since there may simply not be room for such long collectors.
Attempts to reduce the length of the assembly by varying the inclination of the ball-carrying sieves are not possible in many cases since fairly steep angles may be required to ensure effective transport of the balls along the sieves to the collecting trough.